<!DOCTYPE html>
<html>
<head>
<title>GoJS Arrowheads</title>
<meta name="description" content="Show all of the predefined kinds of arrowheads for links." />
<!-- Copyright 1998-2016 by Northwoods Software Corporation. -->
<meta charset="UTF-8">
<script src="go.js"></script>
<link href="../assets/css/goSamples.css" rel="stylesheet" type="text/css" />  <!-- you don't need to use this -->
<script src="goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
<script id="code">
  function init() {
    if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
    var $ = go.GraphObject.make;  // for conciseness in defining templates

    var myDiagram =
      $(go.Diagram, "myDiagramDiv",  // create a Diagram for the DIV HTML element
        {
          isReadOnly: true,  // don't allow move or delete
          initialContentAlignment: go.Spot.Center,
          layout: $(go.CircularLayout,
                    {
                      radius: 100,  // minimum radius
                      spacing: 0,   // circular nodes will touch each other
                      nodeDiameterFormula: go.CircularLayout.Circular,  // assume nodes are circular
                      startAngle: 270  // first node will be at top
                    }),
          // define a DiagramEvent listener
          "LayoutCompleted": function(e) {
              // now that the CircularLayout has finished, we know where its center is
              var cntr = myDiagram.findNodeForKey("Center");
              cntr.location = myDiagram.layout.actualCenter;
            }
        });

    // construct a shared radial gradient brush
    var radBrush = $(go.Brush, "Radial", { 0: "#550266", 1: "#80418C" });

    // these are the nodes that are in a circle
    myDiagram.nodeTemplate =
      $(go.Node,
        $(go.Shape, "Circle",
          {
            desiredSize: new go.Size(28, 28),
            fill: radBrush, strokeWidth: 0, stroke: null
          }), // no outline
        {
          locationSpot: go.Spot.Center,
          click: showArrowInfo,  // defined below
          toolTip:  // define a tooltip for each link that displays its information
              $(go.Adornment, "Auto",
                $(go.Shape, { fill: "#EFEFCC" }),
                $(go.TextBlock, { margin: 4 },
                  new go.Binding("text", "", infoString).ofObject())
              )
        }
      );

    // use a special template for the center node
    myDiagram.nodeTemplateMap.add("Center",
      $(go.Node, "Spot",
        {
          selectable: false,
          isLayoutPositioned: false,  // the Diagram.layout will not position this node
          desiredSize: new go.Size(200, 200),
          locationSpot: go.Spot.Center
        },
        $(go.Shape, "Circle",
          { fill: radBrush, strokeWidth: 0, stroke: null }), // no outline
        $(go.TextBlock, "Arrowheads",
          { margin: 1, stroke: "white", font: "bold 14px sans-serif" })
      ));

    // all Links have both "toArrow" and "fromArrow" Shapes,
    // where both arrow properties are data bound
    myDiagram.linkTemplate =
      $(go.Link,  // the whole link panel
        { routing: go.Link.Normal },
        $(go.Shape,  // the link shape
          // the first element is assumed to be main element: as if isPanelMain were true
          { stroke: "gray", strokeWidth: 2 }),
        $(go.Shape,  // the "from" arrowhead
          new go.Binding("fromArrow", "fromArrow"),
          { scale: 2, fill: "#D4B52C" }),
        $(go.Shape,  // the "to" arrowhead
          new go.Binding("toArrow", "toArrow"),
          { scale: 2, fill: "#D4B52C" }),
        {
          click: showArrowInfo,
          toolTip:  // define a tooltip for each link that displays its information
              $(go.Adornment, "Auto",
                $(go.Shape, { fill: "#EFEFCC" }),
                $(go.TextBlock, { margin: 4 },
                  new go.Binding("text", "", infoString).ofObject())
              )
        }
      );

    // collect all of the predefined arrowhead names
    var arrowheads = go.Shape.getArrowheadGeometries().toKeySet().toArray();
    if (arrowheads.length % 2 === 1) arrowheads.push("");  // make sure there's an even number

    // create all of the link data, two arrowheads per link
    var linkdata = [];
    var i = 0;
    for (var j = 0; j < arrowheads.length; j = j + 2) {
      linkdata.push({ from: "Center", to: i++, toArrow: arrowheads[j], fromArrow: arrowheads[j + 1] });
    }

    myDiagram.model =
      $(go.GraphLinksModel,
        { // this gets copied automatically when there's a link data reference to a new node key
          // and is then added to the nodeDataArray
          archetypeNodeData: {},
          // the node array starts with just the special Center node
          nodeDataArray: [{ category: "Center", key: "Center"}],
          // the link array was created above
          linkDataArray: linkdata
        });
  }

  // a conversion function used to get arrowhead information for a Part
  function infoString(obj) {
    var part = obj.part;
    if (part instanceof go.Adornment) part = part.adornedPart;
    var msg = "";
    if (part instanceof go.Link) {
      var link = part;
      msg = "toArrow: " + link.data.toArrow + ";\nfromArrow: " + link.data.fromArrow;
    } else if (part instanceof go.Node) {
      var node = part;
      var link = node.linksConnected.first();
      msg = "toArrow: " + link.data.toArrow + ";\nfromArrow: " + link.data.fromArrow;
    }
    return msg;
  }

  // a GraphObject.click event handler to show arrowhead information
  function showArrowInfo(e, obj) {
    var msg = infoString(obj);
    if (msg) {
      var status = document.getElementById("myArrowheadInfo");
      if (status) status.textContent = msg;
    }
  }
</script>
</head>
<body onload="init()">
<div id="sample">
  <h3>GoJS Arrowheads</h3>
  <!-- The DIV for the Diagram needs an explicit size or else we won't see anything.
       Also add a border to help see the edges. -->
  <div id="myDiagramDiv" style="border: solid 1px black; width:600px; height:500px"></div>
  <div id="myArrowheadInfo" style="color:red"></div>
  <p>This sample displays all predefined GoJS arrowheads. Select or hover over a Node or its Link to see the names of the arrowheads on the Link.</p>
  <p>
    Each Link shows two arrowheads.
    The Link template has a Shape whose <a>Shape.toArrow</a> property is bound to an arrowhead name.
    A different Shape in the template has its <a>Shape.fromArrow</a> property bound to a different arrowhead name.
    Each arrowhead has been scaled up to make it more easily visible.
  </p>
  <p>See the definitions of all these arrowheads in the file: <a href="../extensions/Arrowheads.js" target="_blank">Arrowheads.js</a>.</p>
  <p>For predefined shape geometries, see the <a href="shapes.html">Shapes</a> sample.</p>
</div>
</body>
</html>